Furnace operating mechanism



Mar 1933- J. P. FERRIS ET AL 1,902,

FURNACE OPERATING MEGI-fANISM Filed Oct. 10, 1930 6 Sheets-Sheet 1 v T v r i rm JUHN F'.FE HRIS. DEINALD ELLJTE. ERNST VVIEDMANN.

March 21, 1933. R s ET AL 1,902,063

FURNACE OPERATING MECHANISM Filed Oct. 10, 1950 6 Sheets-Sheet 2 DUNALD BLLITE.

arming" March 21, 1933. J. P. FERRIS ET AL FURNACE OPERA'T ING MECHANI SM Filed Oct. 10. 1930 6 Sheets-Sheet 3 JEJHN 1:.FEHFHS. DIIINALD ELLJTE 3% ERNST WEEJMANN.

W dfllozmeq March 21, 1933.

J. P. FERRIS ET AL FURNACE OPERATING MECHANISM Filed Oct. 10, 1930 6 Sheets-Sheet 4 I l I l 'll/A DONALD GLUTE. EHNS T 'WIED ANN.

MW w

March 1933- J. P. FERRIS ET AL 1,902,063

FURNACE OPERTING MECHANISM Filed Oct. 10, 1930 6 Sheets-Sheet 5 Fig. 5 A.

g I F 5/ 5a JUHN1:].F1ERRIS. l /5 159 [54 v DU 'ALD BLLJTE. t 07 ERNST "VVIEDMANN. I

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Patented Mar. 21, 1933 UNITED STATES PATENT OFFICE JOHN P. FERRIS, OF W'HITEFISH BAY, WISCONSIN, DONALD CLUTE, OF DETROIT, MICHI- GAN, AND ERNST WIEDMANN, 0F MILWAUKEE, WISCONSIN, ASSIGNORS TO...THE OILGEAR COMPANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN FURNACE OPERATING MECHANISM Application filed October 10, 1930. Serial No. 487,698.

with an elevator for lifting the material clear of the supports and passing it step by step into and through the heating chamber.-

In operation, untreated material is placed upon the conveyor in front of the heating chamber, the doors are opened andthe elevator is raised to lift this material and the material within the furnace clear of the supports. The conveyor is then advanced a predetermined distance or step to move the untreated material into the heating chamber through its front door and to move the material Within the heating chamber forward one step, the treated material at the extreme rear end of the heating chamber being carried outwardly through the rear door. The elevator is then lowered to deposit the untreated and partly treated material upon .the supports and the conveyor is then retracted to its initial are closed.

If the movable units are started and stopped suddenly, undue stresses are created position and the doors in the operating mechanism and a considerable diiferential is caused between movement of the conveyor and the movement of the material to be treated.

The prior furnaces of this character were operated by electric motors through gear drives which are not easily controlled to gradually accelerate and decelerate the movable units, also, the electric and mechanical apparatus is unduly complicated.

An object of the invention is to smoothly and uniformly accelerate and decelerate the movable units.

Another object is to operate the furnace mechanism hydraulically.

Another object is to provide hydraulic furnace-operating mechanism which issimple in construction and easily controlled.

, Another object is to provide hydraulic furnace-operating mechanism which is automatic in operation. I

Another object -is to provide hydraulic furnace-operating mechanism which is tive and precise in operation.

According to the invention as it is ordinarily embodied, the movable units are operated by hydraulic motors which are automatically controlled to gradually accelerate and decelerate the loads.

The invention further provides drives for operating the elevator and conveyor in sequence and a separate drive for operating the doors either in sequence with the elevator and conveyor movements or in unison with the elevator movement.

An embodiment of the invention is illustrated in the accompanying drawings, in which the views are as follows:

posi- Fig. 1 is a top plan view, partly in section, v

of a continuous furnace in which the invention is incorporated.

Fig. 2 is a longitudinal section on the line 22 of Fig. 1, showing the elevator lowered.

Fig. 3 is alongitudinal section showing the elevator raised.

Fig. 4 is a transverse section on a line 4-4 of Fig. 1.

Figs. 5 and 5A taken together form a schematic drawing of the hydraulic circuit and show the valve plungers in certain characteristic positions.

Figs. 6 and 7 are schematic drawings showing the valve plungers in other characteristic positions.

The furnace comprises, in general, a heating chamber 1 having longitudinal stationary supporting bars 2 arranged intermediate its top and bottom for supporting the material to be treated, a conveyor 3 for passing the material into and through the heating chamber, and automatically controlled hydraulic operating mechanism.

The bars 2 are arranged in the chamber 1 in fixed positions, as by having their ends secured in the end walls thereof, and the number of bars required is dependent upon at or below the tops of the supporting bars 2 and the front and rear ends of the chamber 1 above the bars 2 are closed, respectively, by two vertically movable doors 4 and 5 which are arranged in guides 6 carriedyby the walls of the chamber 1.

The doors 4 and 5 are raised and lowered by a hydraulic motor 7 and, preferably, are

counterweighted to lessen the power requiredto operate them.

As shown,'the piston 8 of the motor 7 has its red 9 connected to a counterweight 10 at the under side thereof, the counterweight 10 is connected at its upper side to a yoke 11 by a cable 12 which passes over a deflector sheave 13 carried by a bracket 14 arranged upon the chamber 1, and the yoke 11 is connected to each of the doors 4 and 5 by a cable 15 which passes over two deflector sheaves 16 and 17 carried, respectively, by brackets 18 and 19 arranged upon, the chamber 1.

The material to be treated is passed into and through the chamber 1 upon conveyor bars 20 which formpart of the conveyor 3 and have theirupper edges normally positioned below thetop of the bars 2. The number of conveyor bars is ordinarily pro-por-. tional to the number of the supporting bars,

such as one conveyor bar being arranged between two adjacent supporting bars, as shown.

Each conveyor bar 20 is connected by a pair of links 21 to a crosshead 22 which is arranged in front of the chamber 1 upon two slides 23 carried by the foundation 24 and secured in fixed positions thereon in any suitable manner.

The crosshead 22 is connected by two piston rods 25 to the pistons 26 of two hydraulic feed meters 27 which are arranged parallel to the chamber 1 and adapted to reciprocate the crosshead 22 upon the slides 23 and thereby reciprocate the conveyor bars 20a v p The two feed motors 27' are hydraulically connected in parallel and mechanically connected to the crosshead 22 at or near the ends thereof in order to reciprocate the same uniformly, irrespective of the variations in load or frictional resistance imposed upon the crosshead at either side of its center.

Each conveyor bar 20 is supported from an elevator bar 28 by a number of grooved cams 29 having arcuate upper and lower ends which are fitted in complementary recesses 30 and 31 formed, respectively, in the lower edge of the conveyor bar 20 and in the upper edge of the elevator bar 28.

Each cam 29 is provided upon each side thereof with a flange 32 which overlaps the sides of the bars 20 and 28 and holds the.

cam against lateral movement, and the recesses 30 and 31 enable the arcuate ends-of the cam to rock therein without moving longitudinally of the bars 20 and 28.

-Each elevator bar 28 is carried by a support 33 which rests upon the bottom of the chambcrl and is provided upon its upper side with a longitudinal groove 34 to receive the lower edge of the bar 28.

The groove 34 holds the bar 28 against lateral movement as it is reciprocated therein by a hydraulic motor 35 which is arranged The door motor 7 is first actuated to raise the doors 4 and 5, the elevator motors 35 are then actuated to raise the conveyor bars 20 and cause the same to lift the material clear of the supporting bars 2, and the feed motors 27 are then actuated to advance the conveyor 3.

The material which has been placed in front of the door 4 upon the conveyor bars 20 is carried into the heating chamber 1 through the front end thereof, the material which was in the chamber 1' is movedrear- Wardly therein, and the material which rested upon the rear end of the supporting bars 2 is carried out of the chamber 1 through the may be sloped, as shown, to enable the material to slide downwardly and away from the chamber 1 when the conveyor 3 is retracted.

Liquid for operating the hydraulic meters is supplied by a variable delivery pump 41 I which is indicated diagrammatically in Fig.

5 and has not been illustrated nor described herein as it is well known and in extensive use. Such a pump is disclosed in Patent No.

valve 47 and a low pressure resistance valve 48 connected in parallel therein.

When the pump 41 is delivering liquid at a certain rate to the rod end of a motor, liquid is being expelled from the head end of that motor at a higher rate, and the quantity of liquid expelled in excess of the requirements of the pump 41 is discharged through the low pressure resistance valve 48 and the suction pipe 46 into a reservoir 49 formed in the lower I part of the pump housing 42..

When the pump 41 is delivering liquid at a-certain rate to the head end of a motor, liquid is being expelled at a lower rate from the rod end thereof and the liquid required by the pump 41 in excess of the amount expelled is drawn from the reservoir 49 through the suction pipe 46 and the check valve 47.

The pump housing 42 also contains a gear pump 50 which draws liquid from the reservoir 49 through a suction pipe 51 and delivers it into a low pressure supply pipe '52 having a relief valve 53 connected thereto through which the output of the gear pump 50 is discharged into the reservoir 49'wh-en it is not being used for control purposes, thereby limiting the hydraulic pressure in the pipe 52.

The pump 41 is ordinarily operated at a constant predetermined speed and its volumetric output is varied by changing its stroke. The stroke of the pump 41 is changed by a stroke changing lever 54 which is shown as having one of its ends pivoted to the pump or its housing and its other end connected to a control rod 55.

By moving the rod 55 to the right, the stroke of the pump 41 may be shortened until the delivery of liquid is substantially zero and, by moving the rod 55 to the left, the stroke of the pump may be lengthened until the maximum volumetric capacity of the pump is reached or until the lever 54 abuts a stop 56 which may be adjusted to regulate the maximum output of the pump.

One end of the control rod 55 functions as a piston or plunger in a. cylinder 57 which is connected by a choke 58 to the supply pipe 43 to subject the endof the rod 55 to the hydraulic pressure therein. The pump 41 thus tends to deliver liquid to the cylinder 65 57 to move the rod 55 and the lever 54 and thereby decrease the volume ofliquid delivered to substantially zero.

The other end of the control rod 55 has a piston 59 secured thereon and arranged with ma cylinder 60 which is connected at its outer end by a pipe 61 to a port 62 formed in a pilot valve 63. The piston 59 is engaged by a plunger 64 which is fitted in the head of the cylinder 60 and engages a piston 65 arrangedin a cylinder 66 secured to or formed integral with the cylinder 59.

The piston 65 is urged inwardly by liquid supplied through a pipe 67 which connects the outer end of the cylinder 66 to a port 68 in the pilot valve 63, and the inward movement of the piston 65 is limited by an adjustable stop bolt' 69 which is threaded through the head of the cylinder 66 and has its head 70 arranged within the piston 65 to abut the outer end thereof as the piston moves inwardly. I

Liquidfor operating the pistons 59 and 65 is supplied to the cylinders 60 and 66 from the gear pump 50 through the pipes 61 and 67, the pilot valve 63 and a pipe 71 which has one of its ends connected to the supply pipe 52 and its other end in communication with a port 72 formed in the pilot valve 63 between the ports 62 and 68. Liquid is discharged from the cylinders 60 and 66 through the pipes 61 and 67, the pilot valve 63 and a drain pipe 73 which is connected to each 'end of the pilot valve 63 and discharges into the reservoir 49. 1

The ports 62, 68 and 72 are controlled by the pilot valve plunger 74 which is normally held in the position shown in Fig. 5 bv a helical compression spring 75 arranged between the head of its right end stem 76 and the end of the valve casing. 3

The plunger 74 is adapted to be moved to the position shown in Fig. 7 by a solenoid 77 which is energized in accordance with the movement ofthe doors 4 and 5, the conveyor 3 and the elevator bars 28 and has its core connected to the left end stem 78 ,of the plunger 74.

The purpose of the stroke-control mechanism just described is to accelerate and decelerate the motors 7, 27 and 35 and thereby gradually accelerate the load carried by each motor from a stationary position to full speed and de'celerate it gradually from full speed to a stationary position.

When the pilot valve plunger 74 is in the position shown in Fig. 5, liquid from the gear pump 50 flows'through the pipes 52 and 71, the valve 63-and the pipe 67 to the cylinder 66 and forces the piston 65 inwardly to the limit determined by the adjustment of the bolt 69. therebv forcing the plunger 64 and the piston 59 to the left and causing the pump 41 to deliver liquid at a predetermined limited rate into the supply pipe 43 until the pressure therein and in the cylinder 57 is sufiicient to overcome the gear pump pressure upon the piston and force the rod 55 to the right until the pump 41 is delivering only 5 suflicient liquid to compensate for slip or leakage.

\Vhen the supply pipe 43 is opened to one of the hydraulic motors, the pressure in the cylinder 57 drops and the liquid in the cylinder 66 forces the rod 55 to the left to a predetermined distance. a switch is closed' to energize the solenoid 77 which moves the pilot valve plunger 74 to the position shown in Fig. 7 and thereby opens the port 62 to 20 the port 72.

Liquidfrom the gear pump 50 will then flow through the pipe 61 into the c linder.

60 and overcome the resistance of the liquid 55 to the left until the pump 41 is at full stroke or untll the lever 54 engages the stop 56. p

As the rod 55 moves to the left, the liquid in the cylinder 57 is expelledthrough the thus causes the rod 55 to move at a relatively slow speed and gradually adjust the pump41 from short to long stroke. The motor and its load are thus started at slow speed and gradually accelerated to full speed.

As the piston of that motor approaches the limit of its movement, a switch is opened todeenergize the solenoid 77 and enable the spring 7 5 to retract the plunger 74, thereby opening the cvlinder 66 to gear pump pressure and opening the port 62 to the dram plpe H gh pressure liquid will then flow through the choke 58 into the cylinder 57 and force the rod 55 to the right and the liquid in the cvlinder 60 will be exhausted through the pipe 61 and the valve 63 into the drain pipe 73. a

As the choke 58 limits the rate at WhlCh liquid is delivered to the cylinder 57, the rod '55 will be moved at a relativelyslow speed and gradually adjust the pump 41 from long to short stroke. The motor and its load will thus be decelerated gradually.

The limited volume of liquid delivered by the pump 41 will now operate the motor at slow speed until its piston reaches the limit of its movement.

The stroke control mechanism thus automatically controls the pump 41 to provide a maximum operating delivery, a mlnlmum operating delivery, and a pressure maintainingdelivery which is sufficient to compensate for slip or leakage. Y

The solenoid 77 is energized by current supin the cvlinder 57, thereb forcing the rod choke 58 which retards the flow thereof and plied from a power line 79 and its operation is controlled by a door-operated switch 80, a conveyor-operated switch 81 and an elevatoroperated switch 82 which are connected in series with the solenoid 77 and in parallel with each other.

The winding of the solenoid 77 has one of its ends connected to one side of the power line 79 by a conductor 83 and its other end connected to a conductor 84 which is connected to the other side of the power line 79 through the switches 80,81 and 82.

The switch has one terminal connected to the conductor 84 and its other terminal connected by a conductor 85 to the power line 79, the switch 81 has one terminal connected to the conductor 84 and its other terminal connected by a conductor 86 to the power line 79, and the switch 82 has one terminal connected by a conductor 87 to, the conductor 84 and its other terminal connected by a conductor 88 to the power line 79.

The switches 80, 81 and 82 are shown diagrammatically as self-closing switches and the switch 82. is shown provided with two movable contacts but other types of switches may be employed, it being only necessary that each switch be opened when the piston of the motor controlling that switch is at the end of its strokein either direction and closed when the piston has moved a predetermined distance from the end of its stroke.

The switch 80 is operated by an actuator 89, which is carried by the door 4 near the top thereof to hold the switch open when the doors are closed, and an actuator 90 which is carried by the door 4 near the bottom thereof to hold the switch closed when the doors are fully open.

When liquid from the pump 41 is directed into the -'motor 7 to move the doors in either direction, the motor 7 will move them at slow speed until the actuator holding the switch 80 open moves out of engagement therewith and allows it to close and then the doors move at high speed until the other actuator opens the switch 80. Thereafter, the doors will move at slow speed to their limit ment in that direction.

The switch 81 is operated by two actuators 91 and 92 which are carried by the crosshead 22 and hold the switch open at each end of the of moveconveyor movement.

When liquid from the pump 41 is directed into the motors 27 to move the pistons 26 thereof in either direction, the conveyor 3 will switch 82 to close and then the elevator bars will be moved at high speed until the actuator 93 engagesthe other movable contact and opens the switch 82. Thereafter, the elevator bars 28 move at slow speed to the limit of their movement in that direction.

The doors, conveyor and elevator are thus.

gradually accelerated and deceleratedand there isno slip or differential in movement between the conveyor and its load of mate-' rial. Consequently, material may be moved uniformly and accurately through the heating chamber 1.

The delivery of liquid from the pump 41 is controlled primarily by an emergency valve 94 which has an inlet port 95 communicating with the supply pipe 43, a return port 96 communicating with the return pipe 45, and a delivery port 97 communicating through a duct 98 with an inlet port 99 formed in a reversing valve 100. i

The ports 95, 96 and 97 are controlled by a plunger 101 which has a handle 102 secured to one end thereof for operating it manually. In case it is desired to stop the furnace-opcrating mechanism instantly, the handle 102 may be drawn outwardly to the limit of its movement and thus open communication between the ports 95 and 96 and cause the liquid delivered by the pump 41 to bypass through the pipe 43, the valve 94 and the pipe 45.

The reversing valve has an exhaust port 103, an exhaust port 104 which is connected.

to the port 103 by a duct 105 and to the port 96 in the valve 94 by a duct 106, a port 107,

arranged intermediate the ports 99 and 103 and connected to a pipe 108 through which liquid is delivered to and returned from one end of each of the motors'7 and 35, and a port 109 arranged intermediate-the ports 99 and 104 and connected to apipe 110 through whichliquid is delivered to and'returned from the otherend of the motors 7 and 35.

The flow of liquid through the valve 100 is controlled by its plunger 111 which is operated hydraulically by liquid supplied fromthe gear pump'50through a pilot valve 112 having a port 113 connected by a pipe 114 to one end of the valve 100 and a port. 115 connected by apipe 116 to the other end; of the valve 100. v Liquid from the gear pump 50 is delivered to the pilot valve 112 through a pipe 117 which is connected to both which has one end connected to the supply pipe 52 and its other end connected to a port 118 formed in the pilot valve 112 between the ports 113 and 115, and liquid is returned to the reservoir 49 through the drain pipe 73 ends of the pilot valve casing. 1

The flow of liquid through the pilot valve 112 is controlled by its' plunger 119 which has its stem connected to one arm of a bell crank lever 120 and held in adjustedpositions by a spring detent 121.

The lever 120 is carried byastationarypivot 122 and has its other arm connected to an operating rod 123 which has its lower end connected to the core of a solenoid 124 and its upper end provided with a roller 125 for engagement with a cam 126 carried byvthe crosshead 22.

The solenoid 124 hasone end of its windingconnected to one side of the power line 79 by a conductor 127 and its other end connected to the other side of the power line 79 through a switch 128 which may be operated manually to energize the solenoid 124 and raise the rod 123 andthereby move the plunger 119 to divert the delivery of liquid from one end of the valve 100 to the other end thereof, the rod123 being held in its upper position by the detent 121.

Raising the rod 123 places the roller 125 in the path of the cam 126 and, as the conveyor 3 approaches the limit ori ts forward movement, the cam 12.6 engages the roller 125 and forces the rod 123 downwardly to return the valve plunger 119 to the position shown in Fig. 5A. The cam 126 may be fixed in position or adjustable upon the crosshead 22 to vary the distance which the. conveyor 3 will move forwardly.

Liquid for raising the doors 4 and 5 is delivered to the motor 7 through the pipe 108 which is connected to the upper end of the motor 7 and has a check valve 129 and a resistance valve 130 connected in parallel therein, and the liquid below the piston 8 is expelled through'the pipe 110-which is connected to the lower end of the motor 7 and has a check valve 131 and a resistance valve 132 connected in parallel therein.

Liquid for advancing the elevator bars 28 is delivered-through the expansion joint 39 which is connected at one end to the head ends of both elevator motors 35 and at its other end to the pipe 108 by a pipe 133 having two resistance valves 134 and 135 connected in parallel therein for-passing liquid in opposite directions.- As the elevator bars 28 advance, liquid is expelled from both motors 35 through the expansion joint 38 which -end of both motors 27 tothe supply pipe '43 and has a check valve 137 connected therein to prevent liquid from flowing in the opposite direction. Consequently, the rod ends of the motor pistons 26 are subjected at all times to the hydraulic pressure created by the ump 41.

en the furnace-operating mechanism is idle, the head end of the motors 27 are open to pump pressure and the outward movement of the pistons 26 is limited by a valve 138 which is connected into the pipe 136 in parallel with the check valve 137 and has its piston 139 connected by a rod 140 to the crosshead 22 and held in closed position thereby against the action of a helical compression spring 141 after the conveyor 3 reaches the limit of its retraction stroke to trap the liq-v uid remaining in the rod ends of the motors 27 and thereby hold the pistons 26 against further movement in that direction.

The connection between the rod 140 and the crosshead 22 is such that, as the conveyor I 3 advances and after the piston 139 has been urged to its open position by the spring 141-, the cross head 22 moves freely over the rod 140. Also, this connection is adjustable in order to vary the point in the conveyor movement at which the valve 138 is closed and thereby vary the distance which the conveyor will be retracted.

The head ends of both motors 27 are connected to a port 142 in a control valve 143 by a pipe 144 having a check valve 145 connected therein which allows free flow of liquid from the motors 27 but prevents the flow of liquid in the opposite direction. The pipe 144 is connected also to another port 146 in the valve 143 by a pipe 147 which has a check valve 148 connected therein to prevent the flow of liquid therethrough from the motors 27. The valve 143 has a port 149- arranged between the ports 142 and 146 and connected by a pipe 150 to the pipe 110 which.

at this time, is open to pump pressure.

Both ends of each motor 27 are thus subject to the pressure created by the pump 41 and,

as the head end of each piston 26 has a greater effective area than the rod end thereof, the

liquid acting upon the head ends of the pistons 26 hold them firmly in stationary positions against the liquid trapped in the rod end of the motors 27. v

The ports 142, 146 and 149 in the valve 143 are controlled by a plunger 151 which has its ends reduced in diameter and functioning as pistons in two cylinders 152-and 153 arranged upon the ends of the valve 143, and the casing of the valve 143 is connected at each end to the drain pipe 73 to provide a free flow of liquid from one end of the valve casing to the other end thereof reciprocates.

The valve 143 is operated 'by liquid supplied from the gear pump 50 through a pilot valve 154 which has a port 155 connected to as the plunger 151 the cylinder 152 by a pipe 156, a port 157 connected to the cylinder 153 by a pipe 158, a port 159 connected to the supply pipe 52 by a pipe 160, and has the ends of its casing connected to the drain pipe 73.

The ports 155, 157 and 159 arecontrolled by a plunger 161 which is moved in one direction by a helical compression spring 162 and in the opposite direction by a solenoid 163. The spring 162 is arranged between one end of the Valve casing and the head 164 of a stem secured to one end of the plunger 161,

and the solenoid 163 has its core secured to .veyor 3 and -has its other terminal connected to the other side of the power line 7 9 by the conductor 88.

The switch 167 is closed as the pistons37 of the elevator motor 35 reach the limit of their advance stroke and itremains closed until the pistons 37 are fully retracted.

As shown, the switch 167 is closed by a reciprocable actuator 168 arranged in a guide 169 which is carried by the crosshead 22 and provided with a spring detent 170 for holding actuator 168'in switch-closing position. The actuator 168 is operated by an arm 171 which is carried by one of the piston rods 36 to engage a lug on the actuator 168 and advance it into switch-closing position as the piston 37 reaches the limit of its advance. The detent holds the actuator in its position until the pistons 37 are nearly retracted and then the arm 171 engages another lug on the actuator 168 and retracts it to allow the switch 167 to open.

With the pumps41 and 50 in operation and the several valve plungers in the position shown in Figs. 5 and 5-A, the cylinder 66 of the stroke-control mechanism is open to gear pump pressure, liquid from the gear pump 50 is reaching the cylinder 153 and the left end of the reversing valve 100 and is holding the valve plungers 111 and 151 in the positions shown; high pressure liquid from the pump 41 is reaching the lower end .of the motor 7, the rod ends of the elevator motors 35 and both ends of the conveyor motors 27 and is holding the doors closed and the elevator bars 28 and the conveyor 3 retracted; and the pressure in the cylinder 57 has urged the stroke-control rod 55 tothe right until the pump 41 is delivering only that amount of liquid required to compensate for slip or leakage.

Assuming that the supporting bars 2 are loaded with material to be heat-treated, the operation of the furnace is as follows:

Untreated material is placed on the conveyor bars 20 in front of the door 4 and the switch 128 is closed which causes the solenoid 124 to be energized and the operating rod 123 to be raised, thereby swinging the lever 120 to move the plunger 119 of the pilot valve 112 to the right and placing the roller 125 in the path of the cam 126. The detent 121 holds 73 the plunger 119 in this position and prevents the rod 123 from dropping when the solenoid is deenergized.

The ports 115 and 118 in the pilot valve 112 are now in communication with each other and liquid from the gear pump 50 flows through the pipes 52 and 117, the valve 112 and the pipe 116 to the right end of the valve 100 and forces the plunger 111 to the position shown in Fig. 6, thereby opening the pipe 108 to the supply pipe 43 and the pipe 110 to the return pipe 45. The liquid in the left end of the valve 100 is expelled through.

the pipe 114 and the valve 112 to the drain pipe 73.

High pressure liquid now flows through the pipe 108 and the check valve 129 to the upper end of the motor 7 and causes the doors 4 and 5 to rise at slow speed until the actuator v 89 moves out of engagement with the switch 80 and allows it to close and actuate the stroke=control mechanism to gradually lengthen-the stroke of the pump 41. Then the doors 4 and 5 rise at full speed until the actuator 90 opens the switch 80 and thereby causes the pump stroke to be gradually shortened and the doors to be raised slowly to their fully open position.

\Vhen the doors are fully open, the piston 8 stalls, the pressure in the pipe 108 rises and I the liquid breaks through the resistance valve 134, enters the motors 35 through the expansion joint 39 and advances the elevator bars 28 to raise the conveyor bars and thereby raise the material clear of the supporting bars 2.

The resistance valve 134 may be omitted and then the doors 4 and 5 and the bars 20 will be raised simultaneously.

The bars 20 are raised at slow speed until the actuator 93 has moved sufficiently to disengage one contact of the switch 82 and allow it to close, are then gradually accelerated to full speedwhich is maintained until the actuator 93 engages the other contact of the switch 82 and opens it. The bars 20 are then decelerated to slow speed which is maintained to the limit of their upward movement.

As the pistons .37 of the elevator motor reach the end of their stroke, the arm 171 moves the actuator 168intoengagement with the switch 167 and closes it, and the, detent 170 holds the actuator 168 -in this position.

Closing the switch 167 causes the solenoid 163 to be energized and move the plunger 161 of the pilot valve 154 to the position shown in Fig. 6 and thus open the port 155 to the port 159 and the port 157 to the drain pipe 73.

Liquid from the gear pump now flows through the valve 154 and the pipe 156 to the in the cylinder 153 is expelled through-the pipe 158 and the valve 154 to the drain'pipe The head ends of the conveyor motors 27 are now open to the return pipe 45 through the pipe 144,the valve 143', the pipes 150 and 110 and the valves 100 and 94 and, as therod ends of the motors 27 are already under pressure, the liquid supplied through the pipe 136 advances the conveyor 3 which then al-. lows the spring141 to open the Valve 138.

The conveyor 3 is advanced at slow speed until the actuator 92 moves out of engagement with the switch 81 and allows it to close, then accelerated to full speed which is maintained until the'actuator 91 opens the switch 81, and then decelerated to slow speed which is maintained to the limit of its movement.

As the conveyor .3 reaches the limit of its forward movement, the cam 126 engages the roller. 125 and forces the rod 123 downwardliquid in the right end of the valve 4 through the pipe 116 and the valve 112 to the drain pipe 73. The pipe 150 is now open to pump pressurebut pressure liquid is prevented from reaching the head ends of the motors 27 by the plunger 151 and the check valve 145.

Pressure liquid now flows through the.

pipe and the expansion joint 38 to the rod ends of the elevator motors 35 and lowers the elevator at slow speed until the actuator 93 allows the switch 82 to close. The elevator is a then accelerated to high speed which is main- As the pistons 37 reach the limit of their elevator-lowering stroke, the arm 171 retracts the a'etuator'168, the switch 167 opens,

the solenoid 163 is deenergized and the spring 162 returns the valve plunger 161 to its initial position to-open the port 157 to the port 159 and the'port 155 to the drain pipe'73. Liquid from thegear pump 50 now flows through the pipe 158 to the cylinder 153 and moves the valve plunger 151 to its initial position, and the liquid in the cylinder 152 is expelled through the pipe 156 and the valve 154 to the drain pipe 73.

The head ends of the cylinders 27 are now open to pump pressure through the pipes 144 and 147, the valve 143, the pipes 150 and 110, the valves 100 and 94 and the pipe 43. The rod ends of the 'motors 27 are open to pump pressure as previously described.

As the head end of each piston 26 has a greater area than the rod end thereof and, as the valve 138 is open, the conveyor 3 is retracted by the force exerted upon the differential areas of the pistons 26 and the liquid in the rod ends of the two motors 27 is expelled through the pipe 136 to the pipe 43 and added to the output of the pump 41.

Consequently, the pump 41 need only supply to the head ends of the motors 27 a volume of liquid equal to the displacement of the rod -The conveyor 3 is retracted. at slow speed until the actuator 91 disengages the switch 81 and allows it to close, then accelerated to full sped which is maintained until the actuator 92 opens the switch 81 and then it is decelerated to slow speed which is maintained to the limit of its movement at which time the crosshead 22 actuates the rod 140 to close the valve 138.

When the conveyor 3 stops, the pressure rises in the pipe 110 and the liquid breaks through the resistance valve 132, enters the lower end of the motor 7 and raises the pis ton 8 to close the doors 4 and 5 which descend slowly until the actuator 90 moves out of engagement with the switch 80 and allows it to close, then accelerate and move at full speed until the actuator 89 engages the switch 80 and opens it and then decelerate and move at slow speed until the doors are fully closed.

The switch 128 may now be closed to start a second cycle of operation.

The furnace operating mechanism disclosed herein is susceptible of various modifications and adaptations without departing from the scope of the invention as hereafter claimed:

The invention is hereby claimed as fol lows:

l. A conveyor, comprising a reciprocable carriage, an elevator connected to said carriage to be reciprocated therewith, a hydraulic motor for advancing and retracting said carriage, a hydraulic motor for raising and lowering said elevator, means for supplying driving liquid to said motors, and means for gradually increasing and decreasing the rate of delivery of liquid to said motors to thereby gradually accelerate and decelerate the movements of said carriage and said elevator.

2. A conveyor, comprising a reciprocable carriage, an elevator connected to said carriage to be reciprocated therewith, a hy-' draulic motor for advancing and retracting said carriage, a hydraulic motor for raising and lowering said elevator, a pump for supplying liquid to said motors tooperate the same, and means for gradually varying the Volumetric delivery of said pump to thereby gradually accelerate and decelerate the movements of said carriage and said elevator.

3. A conveyor, comprising a reciprocable carriage, an elevator connected to said carriage to be reciprocated therewith, a hydraulic motor for advancing and retracting said carriage, a hydraulic motor for raising and lowering said elevator, a pump, means for directing liquid from said pump to said elevator motor to operate the same, and means automatically operable at each end of each elevator movement for diverting said liquid into said carriage motor whereby said elevator and said carriage are operated in sequence.

4. A conveyor, comprising a reciprocable carriage, an elevator connected to said carriage to bereciprocated therewith, a hydraulic. motor for advancing and retracting said carriage, a hydraulic motor for raising and lowering said elevator, a variable delivery pump for supplying liquid to said motors to operate the same, and means for gradually varying the stroke of said pump to thereby gradually accelerate and decelerate the movements of said carriage and said elevator.

5. A- conveyor, comprising a reciprocable carriage, an elevator connected to said carriage to be reciprocated therewith, a hydraulic motor for advancing and retracting said carriage, a hydraulic motor for raising and lowering said elevator, a pump for supplying liquid to said motors to operate the same, means for controlling the operation of said motors to raise said elevator then advance said carriage then lower said elevator and retract saidcarriage, and means for gradually accelerating and decelerating each movement ofsaid elevator and said carriage.

6. A conveyor, comprising a reciprocable carriage, an elevator connected to said carriage to be reciprocated therewith, a hydraulic motor for advancing and retracting said carriage, a hydraulic motor for raising and lowering said elevator, a constant speed variable delivery pump for supplying liquid to said motors to operate the same, means for controlling the operation of said motors to raise said elevator then advance said care riage then lower said elevator and retract said carriage, and means for automatically changing the stroke of said pump near the beginning and end of each movement of said elevator and carriage to thereby graduallyriage to be reciprocated therewith, a hydraulic motor for advancing and retracting said carriage, a hydraulic motor for raising and lowering said elevator, a variable delivery pump for supplying liquid to said motors to operate the same, and hydraulically operated means for gradually varying the stroke of said pump .to thereby gradually accelerate and decelerate the movements of said carriage and said elevator.

8. A conveyor, comprising a reciprocable carriage, an elevator connected to said carriage to. be reciprocated therewith, a hydraulic motor for advancing and retracting said carriage, a hydraulic motor for raising and lowering said elevator, a variable delivery pump, means for directing liquid from said pump to said elevator motor to operate the same, and means automatically operable at each end of each elevator movement for diverting said liquid into said carriage motor whereby said elevator and said carriage are operated in sequence, and hydraulically operated means for gradually varying the stroke of said pump to thereby gradually accelerate and decelerate the movements of said carriage and said elevator.

9. A conveyor, comprising a reciprocable carriage, an elevator connected to said carriage to be reciprocated therewith, a hydraulic motor. for advancing and retracting said carriage, a hydraulic motor for raising and lowering said elevator, a variable delivery pump for supplying liquid to said motors to operate the same, hydraulic means for gradually varying the stroke of said pump to thereby gradually accelerate and decelerate the movementsof said carriage and said elevator, a pilot valve for controlling the operation of said hydraulic means, and means operated in accordance with the movements of said elevator and carriage for controlling said pilot valve.

10. A furnace, comprising a heating chamber, a door for closing said chamber, supports arranged within said chamber for carrying the material to be treated, an elevator for raising said material above said supports and for lowering the same onto said supports, a carriage for advancing and retracting said elevator, means for operating said door, elevator and carriage, and means for controlling said operating means to gradually accelerate and decelerate each movement of said door, elevator and carriage.

11. A furnace, comprising a heating chamber, a door for closing said chamber, supports arranged within said chamber for carrying the material to be treated, an elevator for raising said material above said supports and for lowering the same onto said supports,

a carriage for advancing and retracting said elevator, means for operating said door, elevator and carriage in sequence, and means door, elevator and carriage, a pump for supplying liquid to said motors to operate the same, and means for controlling the delivery of liquid from said pump to said motors.

13. A furnace, comprising a heating chamber, a door for closing said chamber, supports arranged within said chamber for carrying the material to be treated, an elevator for raising said material above said supports and for lowering the same onto said supports, a

carriage for advancing and retracting said elevator, hydraulic motors for operating said door, elevator and carriage, a pump for supplying liquid to said motors to operate the same, and means for gradually varyin the output of said pump to vary the speed 0? said motors and thereby gradually accelerate and decelerate each motion of said door, elevator and carriage.

14:. A furnace, comprising a heating chamber, a door for closing said chamber, supports arranged within said chamber for carrying the material to be treated, an elevator for raising said material above said supports and for lowering the same onto said supports, a carriage for advancing and retracting said elevator, hydraulic motors for operating said door, elevator and carriage, a variable delivery pump for supplying liquid to said motors to operate the same, and means for gradually changing the stroke of said pump to vary the speed of said motors and thereby gradually accelerate and decelerate each motion of said door, elevator and carriage. i

15. A furnace, comprising a heating chamber, a door for closing said chamber, supports arranged within said chamber for carrying the material to be treated, an elevator for raising said material above said supports and for lowering the same onto said supports, a carriage for advancing and retracting said elevator, hydraulic motors for operating said door, elevator and carriage in sequence, a variable delivery pump for supplying liquid to said motors to operate'the same, and means for gradually changing the stroke of said pump to vary thespeed of said motors and thereby gradually accelerate and decelerate each motion of said door, elevator and carriage. i

her, a door for closing said chamber, supports 16. A furnace, comprising a heating'chamthe material to be treated, an elevator for raising said material above said supports and for lowering the same onto said supports, a carriage for advancing and retracting said elevator, hydraulic motors for operating said door, elevator and carriage, a variable delivery pump for supplying liquid to said motors to operate the same, hydraulic means for gradually changing the stroke of said pump to vary the speed of said motors and thereby gradually accelerate and deceleratc each motion of said door, elevator and carriage, a pilot valve for controlling said hydraulic means, and means operated in accordance with the movements of said door, elevator and carriage for controlling said pilot valve.

17. A furnace, comprising a heating chamber supports arranged within said chamber to carry material to be heated, means for raising the material substantially free from said supports and moving it forwardly a predeterminated distance and then lowering it onto said supports to thereby advance the material through said chamber intermittently, hydraulic means for operating the aforesaid means, means for supplying driving liquid to said hydraulic means, and means for controlling and varying the delivery of liquid to said hydraulic means to cause said material to be gradually accelerated from a stationary position to a predetermined speed and gradually decelerated to a stationary position.

18. A furnace, comprising a heating chamber, supports arranged within said chamber to carry'material to be heated, means for raising the material substantially free from said supports and moving it forwardly a predetermined distance and then lowering it onto said supports to thereby advance the material through said chamber intermittently, hydraulic means for operating the aforesaid means, a variable delivery pump for supplying driving liquid to said hydraulic means, and means for controlling and varying the output of said pump to thereby cause said material to be gradually accelerated from a stationary position to a predetermined speed and gradually decelerated to a stationary position. a 19. A furnace, comprising a heating chamber, a door for closing said chamber, supports arranged within said chamber for carrying material to be heated, means for raising the material substantially free from said supports and moving it forwardly a predetermined distance and then lowering it upon said supports to thereby advance the material through said chamber intermittently, hydraulic motors for operating said means and for opening and closing said door. a pump for supplying liquid to said motors to operate the same, and means for controlling and varying the delivery of liquid to said motors to cause said door and the material to be accelerated from stationary positions to predetermined speeds and decelerated to stationary positions.

20. A furnace, comprising a heating chamher, a door for closing said chamber, supports arranged within said chamber for carrying material to be heated, means for raising the material substantially free from said supports and moving it forwardly a predetermined distance and then lowering it upon said supports to thereby advance the material through said chamber intermittently, hydraulic motors for operating said means and for opening and closing said door, a variable delivery pump for supplying-liquid to said motors to operate the same, and means for varying the output of said pump to thereby'cause said door and the material to be accelerated from stationary positions to predetermined speeds and decelerated to stationarypositions.

JOHN P. FERRIS. DONALD CLUTE. ERNST WIEDMANN. 

